Answer
$(3x^n+4)^2$
Work Step by Step
RECALL:
$a^2+2ab+b^2=(a+b)^2$
The given trinomial can be written as:
$(3x^n)^2+2(3x^n)(4)+4^2$
This is in the same form as the formula above where $a=3x^n$ and $b=4$.
Use the formula above to have:
$=(3x^n+4)^2$
